Drop Python 2.6 support

Python 2.6 is not supported nor tested anymore, so remove all traces of
it.

Change-Id: I39ee9162999ccbfd966e8ade16d8d1fc50dbdb82

debian/control

@@ -6,7 +6,7 @@ Uploaders: John Wood <john.wood@rackspace.com>,
  Douglas Mendizabal <douglas.mendizabal@rackspace.com>
 Build-Depends: debhelper (>= 9), python
 Standards-Version: 3.9.3
-X-Python-Version: >= 2.6
+X-Python-Version: >= 2.7
 Homepage: http://launchpad.net/barbican
 Vcs-Browser: https://github.com/jfwood/barbican
 Vcs-Git: git://github.com/jfwood/barbican.git

doc/source/testing.rst

@@ -15,16 +15,13 @@ refer to the `tox documentation`_ for assistance.
 Unit Tests
 ------------
 
-Currently, we provide tox environments for Python 2.6 and 2.7. By default
+Currently, we provide tox environments for Python 2.7. By default
 all available test environments within the tox configuration will execute
 when calling ``tox``. If you want to run them independently, you can do so
 with the following commands
 
 .. code-block:: bash
 
-    # Executes tests on Python 2.6
-    tox -e py26
-
     # Executes tests on Python 2.7
     tox -e py27
 

requirements.txt

@@ -2,7 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 alembic>=0.7.1
-argparse
 Babel>=1.3
 cryptography>=0.4 # Apache-2.0
 eventlet>=0.15.2

setup.cfg

@@ -16,7 +16,6 @@ classifier =
     Programming Language :: Python
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
-    Programming Language :: Python :: 2.6
 
 [files]
 packages =